Diagram for 20V engines (two
crankshaft positions)
1 Cylinder A1 is in firing TDC
2 Cylinder A1 is in overlap TDC
I Inlet valve
X Exhaust valve
Checking valve clearance at two crankshaft positions
1.
Check TDC position of piston in cylinder A1:
• If the rocker arms are unloaded on cylinder A1, the piston is in firing TDC.
• If the rocker arms are under load on cylinder A1, the piston is in overlap TDC.
2.
Check valve clearance with cold engine:
• Inlet valves (long rocker arm) = 0.2 mm
• Exhaust valves (short rocker arm) = 0.5 mm
3.
Check all valve clearances in two crankshaft positions (firing TDC and overlap TDC of cylinder A1) as
per diagram.
4.
Use feeler gauge to determine the distance between valve bridge and rocker arm.
5.
If the deviation from the set value exceeds 0.1mm, adjust valve clearance.
Adjusting valve clearance
1.
Release locknut (1).
2.
Insert feeler gauge (3) between valve
bridge and rocker arm.
3.
Using Allen key, set adjusting screw (2) so
that the specified valve clearance is
reached.
4.
Feeler gauge (3) must just pass through the
gap.
5.
Tighten locknut (1) with torque wrench to the specified tightening torque, holding the adjusting screw (2)
to prevent it from turning.
Name
Size
Type
Lubricant
Value/Standard
Nut
M16 x 1.5 Tightening torque
(Engine oil)
90Nm +9Nm
6.
Replace or rectify adjusting screws and/or locknuts which do not move freely.
7.
Check valve clearance.
MS150049/02E 2012-11 | Task Description | 87
TIM-ID: 0000004357 - 007
